Despite my complaint to my children, the lightest material on Earth is not my wallet after a trip to the toy store. It's a new nickel-phosphorus "microlattice" cooked up by scientists.
Behold, the world's lightest material:
It actually consists of 99.99 percent air. The other 0.01 percent is made up of interconnected hollow tubes with a wall thickness of 100 nanometers. That's 1,000 times thinner than a human hair.
To get technical about it, the density of the material is 0.9 milligrams per cubic centimeter. In comparison, the lightest sample of aerogel, the stuff that's been called "solid smoke," has a density of 1.1 mg/cc.
The microlattice is made through a process that's completely different from the "cooking" technique that gives rise to aerogel. The researchers start by setting up a matrix of polymer lattices, and then deposit thin films of nickel-phosphorus. When the polymer is etched away, tiny metal tubes are left behind in the shape of the lattice.
Aerogel is foamy stuff that makes a great insulator but chips off easily. In contrast, the highly ordered structure of the microlattice makes it strong and resilient.